perf bpf: Fix build with libbpf 0.7.0 by adding prototype for bpf_load_program()

The bpf_load_program() prototype appeared in tools/lib/bpf/bpf.h as
deprecated, but nowadays its completely removed, so add it back for
building with the system libbpf when using 'make LIBBPF_DYNAMIC=1'.

This is a stop gap hack till we do like tools/bpf does with bpftool,
i.e. bootstrap the libbpf build and install it in the perf build
directory when not using 'make LIBBPF_DYNAMIC=1'.

That has to be done to all libraries in tools/lib/, so tha we can
remove -Itools/lib/ from the tools/perf CFLAGS.

Noticed when building with LIBBPF_DYNAMIC=1 and libbpf 0.7.0 on RHEL9.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/bpf-event.c

@@ -36,6 +36,11 @@ struct btf *btf__load_from_kernel_by_id(__u32 id)
 #endif
 
 #ifndef HAVE_LIBBPF_BPF_PROG_LOAD
+LIBBPF_API int bpf_load_program(enum bpf_prog_type type,
+				const struct bpf_insn *insns, size_t insns_cnt,
+				const char *license, __u32 kern_version,
+				char *log_buf, size_t log_buf_sz);
+
 int bpf_prog_load(enum bpf_prog_type prog_type,
 		  const char *prog_name __maybe_unused,
 		  const char *license,